Reinforcing sheet for resin molded product, and structure and method for reinforcing resin molded product

ABSTRACT

A reinforcing sheet for a resin molded product includes a constraining layer, and a reinforcing layer laminated on the constraining layer. The reinforcing layer is formed of an adhesive composition containing a polymer and a tackifier. The tackifier contains a high-softening-point tackifier having a softening point of not less than 120° C.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Application No.2011-201603 filed on Sep. 15, 2011, the content of which is hereinincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reinforcing sheet for resin moldedproduct, and a structure and method for reinforcing a resin moldedproduct, and particularly to a reinforcing sheet for a resin moldedproduct, and a structure and method for reinforcing a resin moldedproduct using the same.

2. Description of the Related Art

Conventionally, resin plates or steel plates used in various industrialproducts have been each processed into a thin plate shape to reduce theweight of each of the products.

Therefore, in an attempt to reinforce the thin resin plate, it has beenknown to, e.g., provide ribs on the inner side of the resin plate.

Also, in an attempt to reinforce the thin steel plate, it has been knownto, e.g., provide a steel-plate reinforcing sheet on the inner side ofthe steel plate.

For example, it is proposed that, after a steel-plate reinforcing sheetincluding a constraining layer, and a reinforcing layer made of a foamcomposition is stuck to the vehicle-body steel plate of an automobile,the reinforcing layer is foamed and cured using heat at a hightemperature (in a range of, e.g., 160 to 200° C.) duringelectrodeposition coating to reinforce the vehicle-body steel plate ofthe automobile (see, e.g., Japanese Unexamined Patent No. 2005-41210).

SUMMARY OF THE INVENTION

However, the ribs are typically molded integrally with a resin plate sothat, during the molding thereof, sinks occur in the surfaces of theportions of the resin plate which are reinforced by the ribs. Thisresults in the problem of impaired outer appearance of the resin plate.

When reinforcement is effected using the steel-plate reinforcing sheetdescribed in Japanese Unexamined Patent No. 2005-41210, the reinforcinglayer of the steel-plate reinforcing sheet needs to be heated to 160 to200° C. to be cured. However, if such a steel-plate reinforcing sheet isstuck to the resin plate and heated to 160 to 200° C., a problem arisesthat the resin plate is degraded or melted.

In addition, after being stuck to a resin plate or steel plate, thereinforcing sheet including the steel-plate reinforcing sheet may beplaced together therewith in an atmosphere at a high temperature (of alevel at which the resin plate is not melted) and, in that case also,the reinforcing sheet including the steel-plate reinforcing sheet isdesired to retain an excellent reinforcing ability.

An object of the present invention is to provide a reinforcing sheet fora resin molded product and a structure and method for reinforcing aresin molded product with which it is possible to maintain a lightweight and excellent outer appearance, easily reinforce a resin moldedproduct while preventing the resin molded product from being degraded ormelted, and also maintain an excellent reinforcing ability in anatmosphere at a high temperature of a level at which the resin moldedproduct is not melted.

A reinforcing sheet for a resin molded product of the present inventionincludes a constraining layer, and a reinforcing layer laminated on theconstraining layer, wherein the reinforcing layer is formed of anadhesive composition containing a polymer and a tackifier, and thetackifier contains a high-softening-point tackifier having a softeningpoint of not less than 120° C.

In the reinforcing sheet for a resin molded product of the presentinvention, it is preferable that the high-softening-point tackifier is aterpene phenol resin and/or a hydrogenated terpene resin.

In the reinforcing sheet for a resin molded product of the presentinvention, it is preferable that a blending ratio of the tackifier basedon 100 parts by mass of the polymer is in a range of 40 to 200 parts bymass.

In the reinforcing sheet for a resin molded product of the presentinvention, it is preferable that the tackifier further contains alow-softening-point tackifier having a softening point of less than 120°C., and the low-softening-point tackifier is an alicyclic saturatedhydrocarbon resin.

In the reinforcing sheet for a resin molded product of the presentinvention, it is preferable that the polymer contains a hydrogenatedproduct of a polymer of a monomer containing a conjugated diene.

Alternatively, the reinforcing sheet for a resin molded product of thepresent invention includes a constraining layer, and a reinforcing layerlaminated on the constraining layer, wherein the reinforcing layer isformed of an adhesive composition containing a polymer, the polymercontains a hydrogenated product of a polymer of a monomer containing aconjugated diene and a copolymerizable monomer which can becopolymerized with the conjugated diene, and a content ratio of thecopolymerizable monomer in the monomer is not less than 35 mass %.

In a structure for reinforcing a resin molded product of the presentinvention, the reinforcing sheet for a resin molded product describedabove is stuck to a resin molded product, and then heated to atemperature of not less than 80° C. to be brought into tight adhesivecontact with the resin molded product to reinforce the resin moldedproduct.

In the structure for reinforcing a resin molded product of the presentinvention, it is preferable that the reinforcing sheet for a resinmolded product is heated in advance to a temperature of not less than80° C. and then stuck to the resin molded product.

A method for reinforcing a resin molded product of the present inventionincludes the steps of sticking the reinforcing sheet for a resin moldedproduct described above to a resin molded product, and heating thereinforcing sheet for a resin molded product and/or the resin moldedproduct to a temperature of not less than 80° C. to bring thereinforcing sheet for a resin molded product into tight adhesive contactwith the resin molded product and thereby reinforce the resin moldedproduct.

In the method for reinforcing a resin molded product of the presentinvention, it is preferable that, in the step of sticking thereinforcing sheet for a resin molded product to the resin moldedproduct, the reinforcing sheet for a resin molded product is heated inadvance to a temperature of not less than 80° C. and then stuck to theresin molded product.

According to the structure and method for reinforcing a resin moldedproduct of the present invention using the reinforcing sheet for a resinmolded product of the present invention, the reinforcing layer of thereinforcing sheet for a resin molded product is stuck to the resinmolded product to allow tight adhesive contact to be provided betweenthe constraining layer and the resin molded product.

In the reinforcing sheet for a resin molded product of the presentinvention, the reinforcing layer is formed of the adhesive compositioncontaining the polymer and the tackifier, and the tackifier contains thehigh-softening-point tackifier having a softening point of not less than120° C. Therefore, even in an atmosphere at a high temperature of alevel at which the resin molded product is not melted, thehigh-softening-point tackifier is not softened to allow the reinforcinglayer to retain its shape. As a result, it is possible to improve therigidity of the reinforcing sheet for a resin molded product in thehigh-temperature atmosphere.

Alternatively, in the reinforcing sheet for a resin molded product ofthe present invention, the reinforcing layer is formed of the adhesivecomposition containing the polymer, the polymer contains thehydrogenated product of the polymer of the monomer containing theconjugated diene and the copolymerizable monomer which can becopolymerized with the conjugated diene, and the content ratio of thecopolymerizable monomer in the monomer is not less than 35 mass %.Therefore, even in an atmosphere at a high temperature of a level atwhich the resin molded product is not melted, the hydrogenated productis not softened to allow the reinforcing layer to retain its shape. As aresult, it is possible to improve the rigidity of the reinforcing sheetfor a resin molded product in the high-temperature atmosphere.

Accordingly, it is possible to reliably reinforce a resin molded productusing such a reinforcing sheet for a resin molded product.

In particular, even in an atmosphere at a high temperature of a level atwhich the resin molded product is not melted, it is possible to maintaina light weight, excellent outer appearance, and the excellentreinforcing ability of the structure for reinforcing a resin moldedproduct, while preventing the resin molded product from being degradedor melted.

Moreover, by sticking the reinforcing sheet for a resin molded productonly to the portion of the resin molded product desired to bereinforced, only the portion can be easily reinforced.

In addition, a simple configuration including the constraining layer andthe reinforcing layer allows the resin molded product to be reinforced,while achieving reductions in the thickness and weight thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative view showing an embodiment of a method forreinforcing a resin molded product of the present invention, in which areinforcing sheet for a resin molded product of the present invention isstuck to a resin molded product to reinforce it,

(a) showing the step of preparing the reinforcing sheet for a resinmolded product and stripping a release film therefrom, and

(b) showing the step of sticking the reinforcing sheet for resin moldedproduct to the resin molded product.

DETAILED DESCRIPTION OF THE INVENTION

A reinforcing sheet for a resin molded product of the present invention(first aspect of the invention) includes a constraining layer, and areinforcing layer laminated on the constraining layer.

The constraining layer is provided so as to impart tenacity to thereinforcing layer after stuck and heated. The constraining layer is inthe form of a sheet, lightweight and thin, and preferably formed of amaterial which can be brought into tight adhesive contact with thereinforcing layer to be integrated therewith. Examples of such amaterial include glass cloth, resin-impregnated glass cloth, nonwovenfabric, metal foil, carbon fiber, and polyester film.

The glass cloth is cloth made of glass fiber, and known glass cloth canbe used.

The resin-impregnated glass cloth is the foregoing glass clothimpregnated with a synthetic resin such as a thermosetting resin or athermoplastic resin, and known resin-impregnated glass cloth can beused. Examples of the thermosetting resin include an epoxy resin, aurethane resin, a melamine resin, and a phenol resin. Examples of thethermoplastic resin include a vinyl acetate resin, an ethylene-vinylacetate copolymer (EVA), a vinyl chloride resin, and an EVA-vinylchloride resin copolymer. Each of the thermosetting resins andthermoplastic resins mentioned above can be used alone or incombination.

Examples of the nonwoven fabric include those formed of fibers such aswood fiber (such as wood pulp), cellulose fiber (e.g., regeneratedcellulose fiber such as rayon, semisynthetic cellulose fiber such asacetate, natural cellulose fiber such as linen or cotton, or blendedyarn thereof), polyester fiber, polyvinyl alcohol (PVA) fiber, polyamidefiber, polyolefin fiber, polyurethane fiber, and cellulose fiber(cellulose fiber derived from linen or a material other than linen).

Examples of the metal foil include known metal foil such as aluminumfoil or steel foil.

The carbon fiber is cloth made of fiber containing carbon as a maincomponent, and known carbon fiber can be used.

Examples of the polyester film include a polyethylene terephthalate(PET) film, a polyethylene naphthalate (PEN) film, and a polybutyleneterephthalate (PBT) film. Preferably, the PET film is used.

Among these examples of the constraining layer, the resin-impregnatedglass cloth is used preferably if consideration is given to adhesion,strength, and cost.

The constraining layer has a thickness in a range of, e.g., 0.05 to 2.0mm, or preferably 0.1 to 1.0 mm.

The reinforcing layer is formed by molding an adhesive composition intoa sheet shape.

The adhesive composition is thermoplastic. Specifically, the adhesivecomposition exhibits thermal adhesiveness (thermally pressure-sensitiveadherence) through heating.

The adhesive composition contains a polymer and a tackifier.

Examples of the polymer include a hydrogenated product (hydride) of apolymer of a monomer including a conjugated diene.

Preferably, the monomer contains the conjugated diene as an essentialcomponent, and contains a copolymerizable monomer which can becopolymerized with the conjugated diene as an optional component.

Examples of the conjugated diene include 1,3-butadiene,isoprene(2-methyl-1,3-butadiene), andchloroprene(2-chloro-1,3-butadiene).

The copolymerizable monomer has at least one double bond, and examplesthereof include an aliphatic vinyl monomer such as ethylene, propylene,and isobutylene(2-methylpropene); an aromatic vinyl monomer such asstyrene, chlorostyrene, and vinyltoluene; and a cyano group-containingvinyl monomer such as (meth)acrylonitrile.

Such a copolymerizable monomer can be used alone or in a combination oftwo or more kinds.

Among these copolymerizable monomers, the aromatic vinyl monomer is usedpreferably.

Specific examples of the polymer include a block or random copolymer ofthe conjugated diene and the copolymerizable monomer and, preferably,the block copolymer is used. Specifically, a styrene-butadiene-styreneblock copolymer (SBS), a styrene-isoprene-styrene block copolymer (SIS),or the like can be used.

Note that the blending ratio of the copolymerizable monomer based on 100parts by mass of the conjugated diene is in a range of, e.g., 5 to 80parts by mass, or preferably 15 to 50 parts by mass.

That is, the blending ratio between the copolymerizable monomer(preferably an aromatic vinyl monomer, or more preferably styrene) andthe conjugated diene (preferably 1,3-butadiene) based on mass is in arange of, e.g., 50 mass % or less/50 mass % or more (mass ratio betweenthe copolymerizable monomer and the conjugated diene), or preferably 40mass % or less/60 mass % or more, and normally 10 mass % or more/90 mass% or less.

In the hydrogenated product of the polymer mentioned above, theunsaturated bond (double bond portion) derived from the conjugated dieneis completely hydrogenated or partially hydrogenated, or preferablycompletely hydrogenated. Specific examples of the hydrogenated productinclude a styrene-ethylene-butylene-styrene copolymer (SEBS, or morespecifically a SEBS block copolymer).

Due to the hydrogenation of the polymer described above, thehydrogenated product does not substantially contain an unsaturated bond,and is therefore less likely to be thermally degraded in ahigh-temperature atmosphere. This allows an improvement in the heatresistance of the reinforcing layer.

The hydrogenated product has a melt flow rate (MFR) in a range of, e.g.,not more than 10 g/10 min, or preferably not more than 5 g/10 min, andnormally not less than 0.1 g/10 min at a temperature of 190° C. and witha mass of 2.16 kg.

The hydrogenated product has a melt flow rate (MFR) in a range of, e.g.,not more than 50 g/10 min, or preferably not more than 20 g/10 min, andnormally not less than 0.1 g/10 min at a temperature of 200° C. and witha mass of 5 kg.

The hydrogenated product has a melt flow rate (MFR) in a range of, e.g.,not more than 50 g/10 min, or preferably not more than 20 g/10 min, andnormally not less than 0.1 g/10 min at a temperature of 230° C. and witha mass of 2.16 kg.

Such a hydrogenated product can be used alone or in a combination of twoor more kinds.

Among these examples of the hydrogenated product, SEBS is usedpreferably.

As the polymer, a combination of, e.g., a polymer (including a polymerbefore being hydrogenated in the production of the hydrogenated product)such as SBS or SIS and the hydrogenated product can also be used.

The tackifier contains a high-softening-point tackifier.

The high-softening-point tackifier is contained in the tackifier so asto improve the adhesion between the reinforcing layer and each of theresin molded product and the constraining layer or improve a reinforcingproperty when the resin molded product is reinforced in an atmosphere ata high temperature of a level at which the resin molded product is notmelted. The high-softening-point tackifier has a softening point of notless than 120° C. Examples of the high-softening-point tackifier includea rosin resin having a softening point of not less than 120° C., aterpene resin (including a terpene-phenol copolymer and a hydrogenatedterpene resin) having a softening point of not less than 120° C., acoumarone-indene resin having a softening point of not less than 120°C., an alicyclic saturated hydrocarbon resin having a softening point ofnot less than 120° C., and a petroleum resin (e.g., a hydrocarbonpetroleum resin such as an aliphatic/aromatic copolymer petroleum resinor an aromatic petroleum resin) having a softening point of not lessthan 120° C.

When the softening point of the high-softening-point tackifier is lessthan the foregoing ranges, it is impossible to improve the reinforcingproperty when the resin molded product is reinforced in an atmosphere ata high temperature of a level at which the resin molded product is notmelted.

The softening point of the high-softening-point tackifier is preferablyin a range of not less than 130° C., more preferably not less than 140°C., particularly preferably not less than 150° C., and also, e.g., notmore than 200° C.

Note that the softening point of the high-softening-point tackifier ismeasured by a ring and ball method.

The weight-average molecular weight of the high-softening-pointtackifier is in a range of, e.g., 100 to 10000, or preferably 500 to5000.

Note that the weight-average molecular weight is measured by a gelpermeation chromatography (GPC) method using a GPC apparatus (HLC-8120GPC available from Tosoh Corporation), and calculated in terms ofequivalent standard polystyrene.

Such a high-softening-point tackifier may be used alone or in acombination of two or more kinds.

The blending ratio of the high-softening-point tackifier based on 100parts by mass of the tackifier is in a range of, e.g., 20 to 100 partsby mass, or preferably 25 to 100 parts by mass.

When the blending ratio of the high-softening-point tackifier is lessthan the foregoing ranges, it may be impossible to achieve a sufficientreinforcing property when the resin molded resin is reinforced in anatmosphere at a high temperature of a level at which the resin moldedproduct is not melted. When the blending ratio of thehigh-softening-point tackifier exceeds the foregoing ranges, it may beimpossible to sufficiently improve the adhesion between the reinforcinglayer and each of the resin molded product and the constraining layer.

As necessary, the tackifier contains a low-softening-point tackifier.

The low-softening-point tackifier is contained in the tackifier so as toimprove the reinforcing property at a high temperature and also improvean adhesive force. The low -softening-point tackifier has a softeningpoint of less than 120° C. Examples of the low-softening-point tackifierinclude a rosin resin having a softening point of less than 120° C., aterpene resin (including a terpene-phenol copolymer and a hydrogenatedterpene resin) having a softening point of less than 120° C., acoumarone-indene resin having a softening point of less than 120° C., analicyclic saturated hydrocarbon resin having a softening point of lessthan 120° C., and a petroleum resin (e.g., a hydrocarbon petroleum resinsuch as an aliphatic/aromatic copolymer petroleum resin or an aromaticpetroleum resin) having a softening point of less than 120° C.

As the low-softening-point tackifier, the alicyclic saturatedhydrocarbon resin is used preferably in terms of compatibility with thehydrogenated product.

The softening point of the low-softening-point tackifier is preferablyin a range of not more than 110° C., and also, e.g., not less than 50°C.

Note that the softening point of the low-softening-point tackifier ismeasured by a ring and ball method.

Such a low-softening-point tackifier may be used alone or in acombination of two or more kinds.

The blending ratio of the low-softening-point tackifier to the tackifieris in a range of, e.g., 20 to 80 mass %, or preferably 25 to 75 mass %.Also, the blending ratio of the low-softening-point tackifier based on100 parts by mass of the high-softening-point tackifier is in a rangeof, e.g., 10 to 300 parts by mass, or preferably 30 to 250 parts bymass.

When the blending ratio of the low-softening-point tackifier is lessthan the foregoing ranges, it may be impossible to sufficiently improvethe adhesion between the reinforcing layer and each of the resin moldedproduct and the constraining layer in an atmosphere at a hightemperature of a level at which the resin molded product is not melted.When the blending ratio of the low-softening-point tackifier exceeds theforegoing ranges, the reinforcing layer may be brittle.

The blending ratio of the tackifier based on 100 parts by mass of thepolymer is in a range of, e.g., 40 to 200 parts by mass, or preferably50 to 170 parts by mass.

When the blending ratio of the tackifier is less than the foregoingranges, it may be impossible to sufficiently improve the adhesionbetween the reinforcing layer and each of the resin molded product andthe constraining layer or sufficiently improve the reinforcing propertywhen the resin molded product is reinforced.

On the other hand, when the blending ratio of the tackifier exceeds theforegoing ranges, the reinforcing layer may be brittle.

To the adhesive composition, in addition to the foregoing components,additives such as a filler, an oxidation inhibitor, a softener (such as,e.g., naphthene oil or paraffin oil), a thixotropic agent (such as,e.g., montmorillonite), a lubricant (such as, e.g., a stearic acid), apigment, an antiscorch agent, a stabilizer, an antioxidant, anultraviolet absorber, an antifungal agent, and a fire retardant can alsobe added at an appropriate ratio.

The filler includes a colorant. Examples of the filler include magnesiumoxide, calcium carbonate (such as, e.g., heavy calcium carbonate, lightcalcium carbonate, or Hakuenka®), magnesium silicate (such as, e.g.,talc), mica, clay, mica powder, bentonite (such as, e.g., organicbentonite), silica, alumina, aluminum hydroxide, aluminum silicate,titanium oxide, carbon black (such as, e.g., insulating carbon black oracetylene black), aluminum powder, and glass balloon. These fillers maybe used alone or in a combination of two or more kinds.

As the filler, calcium carbonate or carbon black is used preferably.

Examples of the oxidation inhibitor include an amine-ketone compound, anaromatic secondary amine compound, a phenol compound (such as, e.g.,pentaerythritoltetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), abenzimidazole compound (such as, e.g., 2-mercaptobenzimidazole), athiourea compound, and a phosphite compound. These oxidation inhibitorscan be used alone or in a combination of two or more kinds. Preferably,the phenol compound or benzimidazole compound is used.

The ratio of the additive to be added based on 100 parts by mass of thehydrogenated product is particularly in a range of, e.g., 1 to 200 partsby mass when the additive is the filler and, e.g., 0.1 to 5 parts bymass when the additive is the oxidation inhibitor.

The adhesive composition can be prepared by blending the individualcomponents described above at the blending ratio described above. Tofurther form the reinforcing layer and laminate the reinforcing layer onthe constraining layer, a direct formation method can be used in whichthe individual components described above are dissolved or dispersed atthe foregoing blending ratio in a known solvent (e.g., an organicsolvent such as toluene) to prepare a solution or dispersion liquid, andthen the obtained solution or dispersion liquid is applied on thesurface of the constraining layer and then dried.

Alternatively, a transfer method can also be used in which the obtainedsolution or dispersion liquid is applied on the surface of a releasefilm described later and then dried to form the reinforcing layer, andthen the reinforcing layer is transferred to the surface of theconstraining layer.

To prepare the adhesive composition to form the reinforcing layer andlaminate the reinforcing layer on the constraining layer, another directformation method can also be used in which the individual componentsdescribed above (except for the solvent described above and water) aredirectly kneaded using, e.g., a mixing roll, a pressure kneader, anextruder, or the like to prepare a kneaded material, which is thenmolded into a sheet shape by, e.g., calendering, extrusion molding,press molding, or the like to form the reinforcing layer, which is thenlaminated on the surface of the constraining layer. Specifically, thekneaded material is disposed between the constraining layer and therelease film (described later) to be sandwiched therebetween, which arethen extended by, e.g., press molding into a sheet shape. Alternatively,another transfer method can also be used in which the formed reinforcinglayer is laminated on the surface of the release film and thentransferred to the surface of the constraining layer.

The reinforcing layer thus formed has a thickness in a range of, e.g.,0.02 to 3.0 mm, or preferably 0.03 to 1.3 mm.

The reinforcing sheet for resin molded product thus obtained has athickness in a range of, e.g., 0.25 to 5.0 mm, or preferably 0.4 to 2.3mm.

When the thickness of the reinforcing sheet for resin molded productexceeds the ranges described above, it may be difficult to achieve areduction in the weight of the reinforcing sheet for resin moldedproduct or the manufacturing cost thereof may be increased. When thethickness of the reinforcing sheet for resin molded product is less thanthe foregoing ranges, it may be impossible to sufficiently improve thereinforcing property.

Note that, in the obtained reinforcing sheet for resin molded product,the release film (separator)stuck to the top surface of the reinforcinglayer (surface thereof opposite to the back surface thereof on which theconstraining layer is stuck) can also be left as necessary for a perioduntil the reinforcing sheet for resin molded product is actually used.

Examples of the release film include known release films such assynthetic resin films such as a polyethylene film, a polypropylene film,and a PET film.

After the reinforcing sheet for resin molded product (the reinforcinglayer thereof) is stuck to a polypropylene plate having a thickness of2.0 mm and heated at 80° C. for 10 minutes, the reinforcing sheet forresin molded product has a bending strength at a displacement of 1 mm at90° C. which is in a range of, e.g., 0.8 to 5.0 N, preferably 1.0 to 4.0N, or more preferably 1.2 to 3.0 N.

Specifically, to measure the bending strength of the reinforcing sheetfor resin molded product stuck to the polypropylene plate at adisplacement of 1 mm at 90° C., the reinforcing layer is first broughtinto contact with the polypropylene plate having a thickness of 2.0 mmto stick the reinforcing sheet for resin molded product to thepolypropylene plate, which are then put into a drier set at 80° C.(temperature for achieving tight adhesive contact) for 10 minutes andbrought into tight adhesive contact with each other to provide alaminate plate.

Thereafter, the laminate plate retrieved from the drier is trimmed intoa piece measuring 150 mm long and 25 mm wide to obtain a test specimen.

Thereafter, in a universal testing machine provided with a thermostaticbath set at 90° C. (measurement temperature), the test specimen isplaced in the thermostatic bath, and the bending strength of the testspecimen at a displacement of 1 mm at 90° C. is measured by a threepoint bending test in which the distance between supporting points isset to 100 mm and the center (lengthwise center and widthwise center) ofthe test specimen is pressed from the polypropylene plate side with anindenter having a diameter of 10 mm at a speed of 50 mm/min.

The measured bending strength is defined to be the bending strength ofthe reinforcing sheet for resin molded product adhesively bonded to thepolypropylene plate at a displacement of 1 mm at 90° C.

In the description given above, the bending strength is calculated onthe condition that the measurement temperature is 90° C. and thedisplacement is 1 mm but, even at a room temperature (25° C.), and adisplacement (other than 1 mm) each described later, the bendingstrength is calculated by performing the same processing.

Note that the foregoing bending strength at a displacement of 1 mm ismeasured as a bending strength (strength) at the time when the indenteris displaced by 1 mm after the initiation of pressing.

If the bending strength at a displacement of 1 mm at 90° C. is withinthe foregoing range, in an atmosphere at a high temperature of a levelat which the resin molded product is not melted, the resin moldedproduct can be sufficiently reinforced.

After the reinforcing sheet for resin molded product (the reinforcinglayer thereof) is stuck to the polypropylene plate having a thickness of2.0 mm and heated at 80° C. for 10 minutes, the reinforcing sheet forresin molded product has a bending strength at a displacement of 2 mm at90° C. which is in a range of, e.g., 1.2 to 8.0 N, or preferably 2.0 to6.0 N.

After the reinforcing sheet for resin molded product (the reinforcinglayer thereof) is stuck to the polypropylene plate having a thickness of2.0 mm and heated at 80° C. for 10 minutes, the reinforcing sheet forresin molded product has a maximum bending strength at 90° C. which isin a range of, e.g., 6.0 to 40.0 N, or preferably 7.5 to 30.0 N.

Note that the maximum bending strength is obtained as a maximum bendingstrength (strength) between the time of initiation of pressing and thetime of fracture of the test specimen.

If the bending strength at 90° C. mentioned above is within theforegoing ranges, the resin molded product can be sufficientlyreinforced in an atmosphere at a high temperature of a level at whichthe resin molded product is not melted.

After the reinforcing sheet for resin molded product (the reinforcinglayer thereof) is stuck to the polypropylene plate having a thickness of2.0 mm and heated at 80° C. for 10 minutes, the reinforcing sheet forresin molded product has a bending strength at a displacement of 1 mm ata room temperature (25° C.) which is in a range of, e.g., 6.0 to 20.0 N,preferably 7.0 to 16.0 N, or more preferably 8.0 to 15.0 N.

After the reinforcing sheet for resin molded product (the reinforcinglayer thereof) is stuck to the polypropylene plate having a thickness of2.0 mm and heated at 80° C. for 10 minutes, the reinforcing sheet forresin molded product has a bending strength at a displacement of 2 mm ata room temperature (25° C.) which is in a range of, e.g., 11.0 to 40.0N, preferably 12.0 to 40.0 N, or more preferably 14.0 to 36.0 N.

After the reinforcing sheet for resin molded product (the reinforcinglayer thereof) is stuck to the polypropylene plate having a thickness of2.0 mm and heated at 80° C. for 10 minutes, the reinforcing sheet forresin molded product has a maximum bending strength at a roomtemperature (25° C.) which is in a range of, e.g., 65.0 to 150.0 N, orpreferably 80.0 to 140.0 N.

If the bending strength at 25° C. mentioned above is within theforegoing ranges, the resin molded product can be sufficientlyreinforced in an atmosphere at a high temperature of a level at whichthe resin molded product is not melted.

After the reinforcing layer is stuck to the polypropylene plate at aroom temperature and heated at 80° C. for 10 minutes, the reinforcingsheet for resin molded product has an adhesive force (post-heatingadhesive force) to the propylene plate which is measured by a 90° peeltest at a peeling speed of 300 mm/min to be, e.g., not less than 2 N/25mm, preferably not less than 3 N/25 mm, or more preferably not less than4 N/25 mm, and also, e.g., not more than 50N/25 mm.

If the post-heating adhesive force of the reinforcing sheet for resinmolded product is within the ranges shown above, the reinforcing layershows adherence through heating. Therefore, the reinforcing sheet forresin molded product can be reliably adhesively bonded to the resinmolded product in an atmosphere at a high temperature of a level atwhich the resin molded product is not melted.

The adhesive force described above is measured according to JIS Z0237(2009).

Note that each of the adhesive forces of the reinforcing sheet for resinmolded product is substantially the same as the adhesive force of thecorresponding reinforcing layer.

The reinforcing sheet for resin molded product of the present inventionis used to reinforce a resin molded product.

The resin molded product is not particularly limited as long as theresin molded product needs reinforcement. For example, a resin moldedproduct used for various industrial products can be used.

Examples of a resin for forming the resin molded product include alow-polarity resin such as polyolefin.

Examples of polyolefin include polypropylene and polyethylene.Preferably, polypropylene is used.

Specific examples of such a resin molded product include the bumper ofan automobile and the instrument panel thereof.

FIG. 1 is an illustrative view showing an embodiment of a method forreinforcing a resin molded product of the present invention, in which areinforcing sheet for a resin molded product of the present invention isstuck to a resin molded product to reinforce it, (a) showing the step ofpreparing the reinforcing sheet for a resin molded product and strippinga release film therefrom, and (b) showing the step of sticking thereinforcing sheet for a resin molded product to the resin moldedproduct.

Next, referring to FIG. 1, a description is given to an embodiment of astructure and method for reinforcing a resin molded product of thepresent invention in which the reinforcing sheet for resin moldedproduct of the present invention is stuck to the resin molded product toreinforce it.

As shown in FIG. 1( a), in a reinforcing sheet for resin molded product1, a reinforcing layer 2 is laminated on a constraining layer 3, and arelease film 6 is stuck as necessary to the top surface of thereinforcing layer 2 (surface thereof opposite to the back surfacethereof on which the constraining layer 3 is laminated).

As shown in FIG. 1( b), the resin molded product 4 is to be used in thevarious industrial products described above, and is formed in, e.g., aplate shape. More specifically, the resin molded product 4 is formed toinclude an outer surface 7 which is recognizable in an outer appearanceand an inner surface 8 which is not recognizable in the outerappearance.

To stick the reinforcing sheet for resin molded product 1 to the resinmolded product 4, as shown by the phantom line in FIG. 1( a), therelease film 6 is stripped first from the surface of the reinforcinglayer 2. Then, as shown in FIG. 1( b), the surface of the reinforcinglayer 2 is brought into contact with the inner surface 8 of the resinmolded product 4, and pressure-bonded thereto as necessary. In thepressure bonding of the reinforcing sheet for resin molded product 1,pressing is performed under a pressure in a range of, e.g., about 0.15to 10 MPa.

Further, as necessary, heating (thermocompression) can also be performedsimultaneously with pressing. That is, the reinforcing sheet for resinmolded product 1 is heated in advance, and then the heated reinforcingsheet for resin molded product 1 is stuck to the resin molded product 4.

Conditions for the thermocompression include a temperature which is in arange of, e.g., not less than 80 C°, preferably not less than 90 C°, ormore preferably not less than 100 C°, and normally not more than theheat resistance temperature of the resin molded product 4. Specifically,the temperature is in a range of, e.g., not more than 130 C°, preferably30 to 120 C°, or more preferably 80 to 110 C°.

Thereafter, the resin molded product 4 to which the reinforcing sheetfor resin molded product 1 is stuck is preferably heated.

The heating temperature is in a range of, e.g., not less than 80 C°,preferably not less than 90 C°, or more preferably not less than 100 C°,and normally not more than the heat resistance temperature of the resinmolded product 4. Specifically, the temperature is in a range of, e.g.,not more than 130 C°, preferably 30 to 120 C°, or more preferably 80 to110 C°. The heating time is in a range of, e.g., 0.5 to 20 minutes, orpreferably 1 to 10 minutes.

When the heating temperature and the heating time are less than theranges shown above, it may be impossible to achieve sufficiently tightadhesive contact between the resin molded product 4 and the constraininglayer 3 or sufficiently improve the reinforcing property when the resinmolded product 4 is reinforced. When the heating temperature and theheating time exceed the ranges shown above, the resin molded product 4may be degraded or melted.

The heating of the resin molded product 4 described above is performedby putting the resin molded product 4 to which the reinforcing sheet forresin molded product 1 is stuck into a drying oven in the drying step ofthe manufacturing of the resin molded product 4.

Alternatively, when the manufacturing of the resin molded product 4 doesnot include the drying step, a partially heating device such as a heatgun is used instead of putting the resin molded product 4 into thedrying oven described above to heat only the reinforcing sheet for resinmolded product 1.

Otherwise, it is also possible to use the heating device described aboveand heat only the resin molded product 4 or each of the reinforcingsheet for resin molded product 1 and the resin molded product 4. Notethat, when only the resin molded product 4 is heated, heat from theheating device is transferred (thermally conducted) to the reinforcingsheet for resin molded product 1 via the resin molded product 4.

Then, the reinforcing sheet for resin molded product 1 is stuck to theresin molded product 4. Thereafter, the reinforcing sheet for resinmolded product 1 and/or the resin molded product 4 is further heated asnecessary such that the reinforcing sheet for resin molded product 1 isbrought into tight adhesive contact with the resin molded product 4. Inthis manner, the structure for reinforcing the resin molded product 4 isformed in which the resin molded product 4 is reinforced by thereinforcing sheet for resin molded product 1.

According to the structure and method for reinforcing the resin moldedproduct 4, by adhesively bonding the reinforcing layer 2 of thereinforcing sheet for resin molded product 1 to the resin molded product4, the constraining layer 3 and the resin molded product 4 can bebrought into tight adhesive contact with each other.

In addition, in the reinforcing sheet for resin molded product 1 of thepresent invention, the reinforcing layer 2 is formed of the adhesivecomposition containing the polymer and the tackifier, and the tackifiercontains a high-softening-point tackifier having a softening point ofnot less than 120° C. Therefore, even in an atmosphere at a hightemperature of a level at which the resin molded product 4 is notmelted, the high-softening-point tackifier is not softened to allow thereinforcing layer 2 to retain its shape. As a result, it is possible toimprove the rigidity of the reinforcing sheet for resin molded product 1in the high-temperature atmosphere.

Accordingly, it is possible to reliably reinforce the resin moldedproduct 4 using the reinforcing sheet for resin molded product 1.

In particular, even in an atmosphere at a high temperature of a level atwhich the resin molded product 4 is not melted, it is possible tomaintain a light weight and excellent outer appearance, and alsomaintain the excellent reinforcing ability of the structure forreinforcing the resin molded product 4, while preventing the resinmolded product 4 from being degraded or melted.

In other words, it is possible to maintain a light weight and excellentouter appearance in an atmosphere at a high temperature (specifically inthe range of 60 to 90° C.) in which the resin molded product 4 is notmelted, but is prone to thermal deformation, and maintain the excellentreinforcing ability of the structure for reinforcing the resin moldedproduct 4, while preventing the resin molded product 4 from beingdegraded or melted.

Moreover, by sticking the reinforcing sheet for resin molded product 1only to the portion of the resin molded product 4 desired to bereinforced, only the portion can be easily reinforced.

In addition, a simple configuration including the constraining layer 3and the reinforcing layer 2 allows the resin molded product 4 to bereinforced while achieving reductions in the thickness and weightthereof.

In the description given above, the reinforcing layer 2 is formed onlyof one sheet made of an adhesive composition. However, as shown by,e.g., the broken line in FIG. 1, nonwoven fabric 5 may also be allowedto intervene in the reinforcing layer 2 at a intermediate point in thethickness direction thereof.

As the nonwoven fabric 5, the same nonwoven fabric as shown above can beused. The nonwoven fabric 5 has a thickness in a range of, e.g., 0.01 to0.3 mm.

To manufacture the reinforcing sheet for resin molded product 1 inaccordance with, e.g., a direct formation method, a first reinforcinglayer is laminated on the constraining layer 3, the nonwoven fabric 5 islaminated on the top surface of the first reinforcing layer (surfacethereof opposite to the back surface thereof on which the constraininglayer 3 is laminated), and then a second reinforcing layer is laminatedon the top surface of the nonwoven fabric 5 (surface thereof opposite tothe back surface thereof on which the first reinforcing layer islaminated).

In accordance with a transfer method, the nonwoven fabric 5 issandwiched between the first reinforcing layer and the secondreinforcing layer from the both top surface and back surface sides ofthe nonwoven fabric 5. Specifically, the first reinforcing layer and thesecond reinforcing layer are formed first on the respective surfaces oftwo release films 6, and then the first reinforcing layer is transferredto the back surface of the nonwoven fabric 5, while the secondreinforcing layer is transferred to the top surface of the nonwovenfabric 5.

By interposing the nonwoven fabric 5, the reinforcing layer 2 can beeasily formed thick in accordance with the strength of the resin moldedproduct 4 desired to be reinforced.

Next, a description is given to a reinforcing sheet for resin moldedproduct as a second aspect of the invention.

Note that, when the layers, materials, the blending ratios, methods, andphysical properties (evaluation) of the reinforcing sheet for resinmolded product as the second aspect of the invention are the same asthose of the reinforcing sheet for resin molded product as the firstaspect of the invention described above, a detailed description thereofis omitted.

An adhesive composition contains a polymer.

The polymer contains a hydrogenated product (hydride) of a polymer of amonomer containing a conjugated diene and a copolymerizable monomerwhich can be copolymerized with the conjugated diene.

As the copolymerizable monomer, an aromatic vinyl monomer is preferablyused, or more preferably, styrene is used.

The content ratio of the copolymerizable monomer in the monomer is in arange of not less than 35 mass %.

When the content ratio of the copolymerizable monomer is less than theforegoing range, the reinforcing property when the resin molded productis reinforced cannot be sufficiently improved.

The content ratio of the copolymerizable monomer is preferably in arange of not less than 40 mass %, and, e.g., not more than 70 mass %, orpreferably not more than 60 mass %.

That is, the blending ratio between the copolymerizable monomer(preferably styrene) and the conjugated diene (preferably 1,3-butadiene)based on mass is 35 mass % or more/65 mass % or less, preferably 40 mass% or more/60 mass % or less, e.g., 70 mass % or less/30 mass % or more,or preferably 60 mass % or less/40 mass % or more.

In other words, the blending ratio of the copolymerizable monomer basedon 100 parts by mass of the conjugated diene is in a range of, e.g., notless than 50 parts by mass, preferably 55 to 200 parts by mass, or morepreferably 60 to 150 parts by mass.

Preferably, the adhesive composition further contains a tackifier so asto improve the adhesion between a reinforcing layer and each of a resinmolded product and a constraining layer or improve the reinforcingproperty when the resin molded product is reinforced.

Examples of the tackifier include the high-softening-point tackifier andthe low-softening-point tackifier each described above.

Among these tackifiers, the low-softening-point tackifier is usedpreferably, or more preferably, an alicyclic saturated hydrocarbon resinhaving a softening point of less than 120° C. is used in terms of thecompatibility with the hydrogenated product.

In the reinforcing sheet for resin molded product of the second aspectof the invention, the reinforcing layer is formed of the adhesivecomposition containing the polymer, the polymer contains thehydrogenated product of the polymer of the monomer containing theconjugated diene and the copolymerizable monomer which can becopolymerized with the conjugated diene, and the content ratio of thecopolymerizable monomer in the monomer is not less than 35 mass %.Therefore, even in an atmosphere at a high temperature (specifically inthe range of 60 to 90° C.) of a level at which the resin molded productis not melted, the hydrogenated product is not softened to allow thereinforcing layer to retain its shape. As a result, it is possible toimprove the rigidity of the reinforcing sheet for resin molded productin the high-temperature atmosphere.

Next, a description is given to a reinforcing sheet for resin moldedproduct as a third aspect of the invention.

The reinforcing sheet for resin molded product as the third aspect ofthe invention is included in each of the first and second aspects of theinvention. In the reinforcing sheet for resin molded product as thethird aspect of the invention, a reinforcing layer is formed of atackifier composition containing the tackifier of the first aspect ofthe invention and the polymer of the second aspect of the invention.

That is, in the reinforcing layer, the tackifier contains ahigh-softening-point tackifier having a softening point of not less than120° C., the polymer contains a hydrogenated product of a polymer of amonomer containing a conjugated diene and a copolymerizable monomerwhich can be copolymerized with the conjugated diene, and the contentratio of the copolymerizable monomer in the monomer is not less than 35mass %.

The reinforcing sheet for resin molded product of the third aspect ofthe invention achieves the same function and effect as achieved by thereinforcing sheet for resin molded product of the first aspect of theinvention and the reinforcing sheet for resin molded product of thesecond aspect of the invention.

EXAMPLES

While in the following, the present invention is described morespecifically with reference to Examples and Comparative Example, thepresent invention is by no means limited thereto.

Examples 1-10

In accordance with the blending formulation shown in Table 1, theindividual components were blended on a part by mass basis, and kneadedwith a mixing roll heated in advance to 120° C. to prepare kneadedmaterials of thermoplastic adhesive compositions.

Then, each of the prepared kneaded materials of the adhesivecompositions was sandwiched between resin-impregnated glass cloth(constraining layer) impregnated with an epoxy resin and having athickness of 0.18 mm and a release film, and extended into a sheet shapeby press molding at 120° C. to produce a reinforcing sheet for resinmolded product having a thickness of 0.8 mm (see FIG. 1( a)). Note thatthe thickness of a reinforcing layer was 0.62 mm.

Comparative Example 1

In accordance with the blending formulation shown in Table 1, theindividual components were blended on a part by mass basis, andprocessed in the same manner as in Examples 1 to 10 to produce areinforcing sheet for resin molded product having a thickness of 0.78 mm(see FIG. 1( a)). Note that the thickness of a reinforcing layer was0.60 mm.

TABLE 1 Content Ratio of Soften- Styrene ing Comp. (Mass Point Ex. Ex.Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. %) (° C.) 1 2 3 4 5 6 7 8 9 10 1Adhe- Poly- Hydro- SEBS Tuftec 30 — 100 100 100 100 100 — — — — — — sivemer genated H1041 Compo- Product Tuftec 67 — — — — — 100 — 50 100 100 —sition of H1043 (Rein- Polymer Tuftec 42 — — — — — — 100 50 — — —forcing H1051 Layer) Polymer SBS Asaprene 30 — — — — — — — — — — 50 T432Tufprene 40 — — — — — — — — — — 50 A Tacki- Terpene Phenol YS — 160 100— 30 — 50 — — — 30 — — fier Resin Polyster T160 Hydrogenated Arkon 150 —100 — 30 50 — — — — 30 — Terpene Resin P150 Alicyclic Arkon 100 — — 7070 — 70 70 70 70 70 — Saturated P100 Hydrocarbon Arkon 100 — — — — — 3030 30 — — — Resin P100 Hydrocarbon Petrotack  88 — — — — — — — — — — 100Petroleum Resin 90HM Filler Heavy Calcium Carbonate 100 100 100 100 100100 100 100 100 100 100 Asahi Carbon #50 1 1 1 1 1 1 1 1 1 1 3 OxidationInhabitor Irganox 1010 2 2 2 2 2 2 2 2 2 2 — Nocrac MB 1 1 1 1 1 1 1 1 11 1

Note that the values of the individual components of each of theadhesive compositions (reinforcing layers) in Table 1 show the numbersof parts of the blended components.

The details of the individual components shown in Table 1 are shownbelow.

Tuftec H1041 is a styrene-ethylene-butylene-styrene block copolymeravailable from Asahi Kasei Chemicals Corporation and having astyrene/ethylene-butadiene ratio of 30 mass %/70 mass %, an MFR (190°C., 2.16 kg) of 0.3 g/10 min, an MFR (200° C., 5 kg)) of 3.5 g/10 min,and an MFR (230° C., 2.16 kg) of 5.0 g/10 min.

Tuftec H1043 is a styrene-ethylene-butylene-styrene block copolymeravailable from Asahi Kasei Chemicals Corporation and having astyrene/ethylene-butadiene ratio of 67 mass %/33 mass %, an MFR (200°C., 5 kg) of 5.0 g/10 min, and an MFR (230° C., 2.16 kg) of 2.0 g/10min.

Tuftec H1051 is a styrene-ethylene-butylene-styrene block copolymeravailable from Asahi Kasei Chemicals Corporation and having astyrene/ethylene-butadiene ratio of 42 mass %/58 mass %, an MFR (200°C., 5 kg) of 0.5 g/10 min, and an MFR (230° C., 2.16 kg) of 0.8 g/10min.

Asaprene T432 (trade name) is a styrene-butadiene-styrene blockcopolymer available from Asahi Kasei Chemicals Corporation and having astyrene/butadiene ratio of 30 mass %/70 mass %.

Tufprene A (trade name) is a styrene-butadiene-styrene block copolymeravailable from Asahi Kasei Chemicals Corporation and having astyrene/butadiene ratio of 40 mass %/60% mass %.

YS Polyster T160 is a terpene-phenol copolymer available from YasuharaChemical Co., Ltd. and having a softening point (measured by a ring andball method) of 160° C., a weight-average molecular weight of 1200(measured by a GPC method based on calculation in terms of equivalentPS), and a glass transition point (measured by a DSC method) of 103° C.

Arkon P150 is a hydrogenated terpene resin available from ArakawaChemical Industries and having a softening point (measured by a ring andball method) of 150° C., a weight-average molecular weight of 750(measured by a GPC method based on calculation in terms of equivalentPS), and a glass transition point (measured by a DSC method) of 93° C.

Arkon P100 is an alicyclic saturated hydrocarbon resin available fromArakawa Chemical Industries and having a softening point (measured by aring and ball method) of 100° C.

Arkon M100 is an alicyclic saturated hydrocarbon resin available fromArakawa Chemical Industries and having a softening point (measured by aring and ball method) of 100° C.

Petrotack 90HM is a hydrocarbon petroleum resin available from TosohCorporation and having a softening point (measured by a ring and ballmethod) of 88° C.

Heavy calcium carbonate is available from Maruo Calcium, Co., Ltd.

Asahi Carbon #50 is carbon black available from Asahi Carbon Co., Ltd.

Irganox 1010 is pentaerythritoltetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] available fromBASF Japan Ltd.

Nocrac MB is 2-mercaptobenzimidazole available from Ouchi ShinkoChemical Industrial Co., Ltd.

(Evaluation)

As Examples 1 to 10 and Comparative Example 1, the obtained bendingstrengths and adhesive forces were evaluated as follows.

The results thereof are shown in Table 2.

(1) Bending Strength of Reinforcing Sheet for Resin Molded Product

The reinforcing sheets for resin molded product of Examples 1 to 10 andComparative Example 1 were stuck to polypropylene plates each having athickness of 2.0 mm such that reinforcing layers came in contact withthe polypropylene plates. The reinforcing sheets for resin moldedproduct and the polypropylene plates were then put into a drier set at80° C. (temperature for achieving tight adhesive contact) for 10 minutesand brought into tight adhesive contact with each other to providelaminate plates. Then, the laminate plates retrieved from the drier wereeach trimmed into pieces each measuring 150 mm long and 25 mm wide toobtain test specimens.

The obtained test specimens were placed in the respective thermostaticbaths of a universal testing machine (available from Minebea Co., Ltd.)set at the measurement temperatures (25° C. and 90° C.) shown in Table 2and, by a three point bending test, a bending strength at a displacementof 1 mm, a bending strength at a displacement of 2 mm, and a maximumbending strength were measured for each of the test specimens.

Note that, in the three point bending test, in the universal testingmachine (available from Minebea Co., Ltd.), the distance betweensupporting points was set to 100 mm and the center (lengthwise centerand widthwise center) of each of the test specimens was pressed from thepolypropylene plate side with an indenter having a diameter of 10 mm ata speed of 50 mm/min.

(2) Adhesive Force After Heating (Post-Heating Adhesive Force) ofReinforcing Layer

Only for the reinforcing layer formed in each of Examples 1 to 10 andComparative Example 1, by a 90° peel test according to JIS Z0237 (2009)at a peeling speed of 300 mm/min, the post-heating adhesive force to thepolypropylene plate was measured.

First, only the reinforcing layer of each of Examples 1 to 10 andComparative Example 1 was stuck to the polypropylene plate at a roomtemperature (25° C.). Then, after the reinforcing layer and thepolypropylene plate were heated at 80° C. for 10 minutes, the adhesiveforce (post-heating adhesive force) of the reinforcing layer to thepolypropylene plate was measured.

TABLE 2 Exs. and Com. Ex Measurement Comp. Temperature Displacement Ex.1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 1 Bending25° C. Displacement of 12.1 8.2 9.1 6.2 10.9 13.3 13.4 13.1 11.0 15.85.9 Strength 1 mm [N] Displacement of 23.6 14.3 16.5 11.6 21.5 25.6 25.324.6 19.7 30.1 11.8 2 mm Maximum 116.1 70.5 82.1 69.1 102.9 125.1 122.9117.3 125.1 133.1 62.7 90° C. Displacement of 2.3 1.5 1.2 1.3 1.8 2.12.1 2.3 2.7 3.0 0.6 1 mm Displacement of 4.1 2.9 2.1 2.3 3.2 4.0 3.8 4.24.9 5.4 1.1 2 mm Maximum 14.4 12.4 7.9 8.6 11.9 19.8 15.2 18.1 25.5 27.75.1 Adhesive Force Post-Heating 2.7 17.8 33.7 25.8 14.8 6.9 24.8 20.18.0 3.2 21.2 [N/25 mm]

While the illustrative embodiments of the present invention are providedin the above description, such is for illustrative purpose only and itis not to be construed limitative. Modification and variation of thepresent invention which will be obvious to those skilled in the art isto be covered by the following claims.

What is claimed is:
 1. A reinforcing sheet for a resin molded product,comprising: a constraining layer; and a reinforcing layer laminated onthe constraining layer, wherein the reinforcing layer is formed of anadhesive composition containing a polymer and a tackifier, and thetackifier contains a high-softening-point tackifier having a softeningpoint of not less than 120° C.
 2. A reinforcing sheet for a resin moldedproduct according to claim 1, wherein the high-softening-point tackifieris a terpene phenol resin and/or a hydrogenated terpene resin.
 3. Areinforcing sheet for a resin molded product according to claim 1,wherein a blending ratio of the tackifier based on 100 parts by mass ofthe polymer is in a range of 40 to 200 parts by mass.
 4. A reinforcingsheet for a resin molded product according to claim 1, wherein thetackifier further contains a low-softening-point tackifier having asoftening point of less than 120° C., and the low-softening-pointtackifier is an alicyclic saturated hydrocarbon resin.
 5. A reinforcingsheet for a resin molded product according to claim 1, wherein thepolymer contains a hydrogenated product of a polymer of a monomercontaining a conjugated diene.
 6. A reinforcing sheet for a resin moldedproduct, comprising: a constraining layer; and a reinforcing layerlaminated on the constraining layer, wherein the reinforcing layer isformed of an adhesive composition containing a polymer, the polymercontains a hydrogenated product of a polymer of a monomer containing aconjugated diene and a copolymerizable monomer which can becopolymerized with the conjugated diene, and a content ratio of thecopolymerizable monomer in the monomer is not less than 35 mass %.
 7. Astructure for reinforcing a resin molded product in which a reinforcingsheet for a resin molded product is stuck to a resin molded product, andthen heated to a temperature of not less than 80° C. to be brought intotight adhesive contact with the resin molded product to reinforce theresin molded product, wherein the reinforcing sheet for a resin moldedproduct includes a constraining layer, and a reinforcing layer laminatedon the constraining layer, the reinforcing layer is formed of anadhesive composition containing a polymer and a tackifier, and thetackifier contains a high-softening-point tackifier having a softeningpoint of not less than 120° C.
 8. A structure for reinforcing a resinmolded product according to claim 7, wherein the reinforcing sheet for aresin molded product is heated in advance to a temperature of not lessthan 80° C. and then stuck to the resin molded product.
 9. A method forreinforcing a resin molded product, comprising the steps of: sticking areinforcing sheet for a resin molded product to a resin molded product;and heating the reinforcing sheet for a resin molded product and/or theresin molded product to a temperature of not less than 80° C. to bringthe reinforcing sheet for a resin molded product into tight adhesivecontact with the resin molded product and thereby reinforce the resinmolded product, wherein the reinforcing sheet for a resin molded productincludes a constraining layer, and a reinforcing layer laminated on theconstraining layer, the reinforcing layer is formed of an adhesivecomposition containing a polymer and a tackifier, and the tackifiercontains a high-softening-point tackifier having a softening point ofnot less than 120° C.
 10. A method for reinforcing a resin moldedproduct according to claim 9, wherein, in the step of sticking thereinforcing sheet for a resin molded product to the resin moldedproduct, the reinforcing sheet for a resin molded product is heated inadvance to a temperature of not less than 80° C. and then stuck to theresin molded product.
 11. A structure for reinforcing a resin moldedproduct in which a reinforcing sheet for a resin molded product is stuckto a resin molded product, and then heated to a temperature of not lessthan 80° C. to be brought into tight adhesive contact with the resinmolded product to reinforce the resin molded product, wherein thereinforcing sheet for a resin molded product includes a constraininglayer, and a reinforcing layer laminated on the constraining layer, thereinforcing layer is formed of an adhesive composition containing apolymer, the polymer contains a hydrogenated product of a polymer of amonomer containing a conjugated diene and a copolymerizable monomerwhich can be copolymerized with the conjugated diene, and a contentratio of the copolymerizable monomer in the monomer is not less than 35mass %.
 12. A structure for reinforcing a resin molded product accordingto claim 11, wherein the reinforcing sheet for a resin molded product isheated in advance to a temperature of not less than 80° C. and thenstuck to the resin molded product.
 13. A method for reinforcing a resinmolded product, comprising the steps of: sticking a reinforcing sheetfor a resin molded product to a resin molded product; and heating thereinforcing sheet for a resin molded product and/or the resin moldedproduct to a temperature of not less than 80° C. to bring thereinforcing sheet for a resin molded product into tight adhesive contactwith the resin molded product and thereby reinforce the resin moldedproduct, wherein the reinforcing sheet for a resin molded productincludes a constraining layer, and a reinforcing layer laminated on theconstraining layer, the reinforcing layer is formed of an adhesivecomposition containing a polymer, the polymer contains a hydrogenatedproduct of a polymer of a monomer containing a conjugated diene and acopolymerizable monomer which can be copolymerized with the conjugateddiene, and a content ratio of the copolymerizable monomer in the monomeris not less than 35 mass %.
 14. A method for reinforcing a resin moldedproduct according to claim 13, wherein, in the step of sticking thereinforcing sheet for a resin molded product to the resin moldedproduct, the reinforcing sheet for a resin molded product is heated inadvance to a temperature of not less than 80° C. and then stuck to theresin molded product.